In many cases it is necessary to insert a catheter or cannula into the body, or a body part of, a patient. By means of the so-inserted cannula, it is then possible to infuse medicinally-required fluid or material. Another reason for the employment of a cannula may be to aid in insertion of a micro-dialysis probe into the body.
To insert a cannula into a patient, a rigid needle is placed within the lumen of the cannula, and the needle and cannula combination is forced into the skin of a patient. Once the cannula combination is fully inserted, the needle is retracted, leaving the cannula in place. When performed manually, the penetration of the catheter-carrying needle into the body, however, may be considered uncomfortable for a patient, or may cause some other anxiety. Also, the subsequent manual withdrawal of the needle is often regarded by some patients as painful.
Automatic cannula insertion devices have been developed to address these issues. Typically, a cannula is included in a stand-alone device called an insertion or injection set. In addition to the cannula and needle, the insertion set often includes a housing to which the cannula is attached during use. The housing may have an adhesive pad for adhering the housing to the skin of the patient during use, as well as an internal void or chamber that is penetrated by an inlet and a septum. The needle passes through the septum, void, and into the lumen of the cannula. After insertion, the needle is withdrawn from the septum, which seals the void. Thereafter, a tube is connected to the inlet, thereby placing the lumen (via the void) in fluidic communication with an infusion device, intravenous (IV) drip bag, or other medical equipment. The above-described insertion sets may be acceptable for some patients, but the attached tube and medical device can be obtrusive, which may be undesirable in some cases. It would be desirable then, to incorporate the functionality of an insertion set into an infusion device to minimize the attendant tubing and complications involved in connecting the insertion set to the infusion device.